1. Field of the Invention
The present invention relates to an apron used for recovering particles of precious materials produced during manufacture of dental or jewelry articles, etc., and the method of using this apron. More particularly, this invention relates to an apron which traps precious metal particles and which, when it has accumulated enough particles, is used, in its entirety, as raw material for a metal recovery process.
2. Description of the Prior Art
It is known that in the manufacture of dental and jewelry articles, and other articles made of precious metals or other materials, signficant amounts of particles are removed by craftsman as a result of grinding or other working processes. Particularly when high-speed grinding tools are used, the precious metal particles which are removed from the workpiece are dispersed over a rather wide area and many are deposited upon the clothing or skin of the craftsman working with the article. Because, in the case of precious metal articles, typical alloys used contain up to seventy or eighty percent gold or silver as well as significant amounts of platinum and palladium, recovery of these particles can have considerable economic importance.
A number of arrangements and methods are known in the prior art which are used to collect precious metal particles produced during metal working operations. Attachments to grinding machinery which use enclosures or suction, or a combination of the two, are knwon; e.g., Luden, U.S. Pat. No. 1,393,892. Also known are cups or receptacles into which a precious metal workpiece and tool are inserted and which form a particle-entrapping enclosure around the workpiece, e.g., Voigt, U.S. Pat. No. 1,742,331. In one such device, the particle-entrapping enclosure also includes a small attached receptacle in which trapped particles are accumulated; e.g., Ousley, U.S. Pat. No. 1,255,040. An additional arrangement, also known in the prior art, is a combination grindings catcher and shield, comprising a formed metal sheet worn by a craftsman working over an open drawer and shaped such that it channels metal particles into the drawer; e.g., Globe, U.S. Pat. No. 2,637,852.
Each of the prior art arrangements and methods for collecting precious metal articles suffers from certain limitations or disadvantages. Enclosure and suction devices fitted to grinding wheels or tables are of limited value because the need for access to the grinding wheel limits the amount of suction which can be generated in the critical area and results in an opening through which particles can escape. Moreover, precious metal particles, being generally of greater weight (and, therefore having greater momentum) than other grindings, tend to escape a suction system. Particle collection cups are unsatisfactory, because they unnecessarily confine the working area available for the craftsman's hands and tools and because they must be carefully cleaned to remove accumulated particles. A metal shield worn by a craftsman is also unsatisfactory, because it is uncomfortable to wear and must be used in conjunction with a drawer at its lower end to collect channeled particles. Accordingly, none of the prior art devices or methods are particularly efficient for particle collection; nor are they easy for a craftsman to use or particularly adapted to a full recovery process.